Vacation
The Vacation application allows you to manage mail "vacation
  notices" or "auto-responders."
Once you set a vacation notice, the system will
  automatically reply to any incoming mail you receive. This can
  be useful while you are away or unable to attend to your mail
  -- for example while on vacation or out of town on business. It
  could be used as a courtesy to let others know why you are not
  answering their mail to you.
Enabling a vacation notice
Check the Set/Install checkbox to
  indicate that you desire to create a vacation notice.
Note: 
If there is an existing vacation or forwards setup, it will be replaced by the
new vacation setup you create here!
There is a large message composition window in the middle
  for you to compose your vacation message. This is the message
  that will be sent to others. A sample message is there, which
  you can edit to your needs.
The vacation message may include mail headers, and should
  include at least a Subject: header. It should NOT, however,
  contain a To: header as that will be generated automatically).
  If the string $SUBJECT appears in the message, it will be
  replaced with the original subject line of the original message
  when the reply is sent.
When ready to submit the vacation notice, enter your
  password into the password box, and press the 
  Submit
  button. At the top of the new page, there will be a message
  letting you know if the new vacation notice was set or not.
  
Disabling a vacation notice
When the vacation notice is no longer needed, you can disable
  it by checking the Unset/Remove checkbox,
  enter your password in the password box, and submitting the form. At the
  top of the new page, there will be a message letting you know
  if the new vacation notice was set or not. Removing the setup
  stops any further vacation notices from being sent.